A turret press lets you mount several dies in the press at the same time. When you move from say full length resizing and decapping to the next stage you just turn the turrett. Turrets are really nice if you load for one cartridge as you would set up all the dies and leave them in the press.
With a single stage press you mount one die and when you are ready to go to the next stage you take it out and put another one in. Single stage presses are thought to be stronger than a turret, and if you're full length resizing large cases a single stage will usually allow for more leverage. I don't find this to be an much of an issue if you lube the cases. Both presses use the same dies.
For reloading pistol ammunition I think a turret may be a little faster, but for rifle ammo it's probably a wash.
The lee loader will do everthing it needs to do, just not as fast , and if you do your part it will provide very accurate ammo.
I would recommend you get an inexpensive beam balance scale and weigh your powder for each load. The measure that comes with the lee will throw different weights depending on the powder.
For accurate loads, a scale will be much more consistent than the measure.
By the way, there is a handload and reloading forum here at Greybeard with loads of information on the subject.